Flood Water Mosquitoes or Why Are There Suddenly So Many Mosquitoes?

Why do I have so many mosquitoes a week after it rains? This is a familiar question for anyone, anywhere in the summer. The answer is floodwater mosquitoes.


These guys, the floodwater mosquitoes, are present in just about every environment from snow melt (not a problem here in Texas) to desert areas that are prone to monsoon type rains. What is unique about this type of mosquito is that they do not lay their eggs in water; but in dry or damp areas prone to flooding. There are many species of floodwater mosquitoes, and each finds the particular place they like best, from hoof prints to grassy areas along side roads. The eggs they lay can survive on dry ground for up to seven years.

The flood water mosquitoes egg laying habits and ability to fly long distances added with Austin’s multiple years of drought have made this summer a perfect year for floodwater mosquitoes. These nasty guys can show up 20 miles from where they are hatched, and lay 200 eggs in their lifetime. Because the eggs can survive drying for long periods, there can be 0.7-1.3 million eggs per acre. After a summer rain, adult mosquitoes can emerge within six days. This means a week after heavy summer rain in Austin, particularly after a few years of drought, there can be millions of new mosquitoes flying around.

Luckily for us, most floodwater mosquitoes don’t live very long, an average of about 2 weeks. For two to three weeks after a heavy storm, there will be many more (millions more) mosquitoes. You can counteract this summer scourge. Floodwater mosquitoes feed primarily at dawn and dusk, so avoid being outdoors at that time. Dress in light colored clothes and use repellents when you are outdoors. Treating your yard for mosquitoes will also be effective, but perhaps less so than for other types of mosquitoes, simply due to the large numbers that simultaneously emerge. And remember, in a couple of weeks they will be gone…until a week after the next heavy rain.



Chikungunya has been in the news a lot lately, but what is it, how do you prevent it, and most importantly, how do you say it?!

Chikungunya (pronounced chick en GUN yah) is a mosquito-borne illness. It cannot be transmitted from human to human, but only from human to mosquito to human. The reason you have never heard of it, although it is common in other parts of the world, is that it only recently arrived in the Americas. In fact, until a week or two ago, the only cases in the United States were people who contracted the disease elsewhere and just happened to be back home when they started to experience the symptoms.

Symptoms of chikungunya include headache, fever, joint pain, rash and in some cases, long term joint issues. There is no vaccine, and it can be painful, but it is seldom fatal. Chronic symptoms are also rare.

The primary carriers of chikungunya are Aedes aegypti (yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito). Both of these species feed during the day, as well as at dawn and dusk. They are cavity nesting mosquitoes and they prefer to lay their eggs in stagnant water with rotting vegetation, or in areas that are currently dry but often fill with water. Their eggs can survive being dried out for long periods. In Texas, the yellow fever mosquito lays eggs almost exclusively in man-made containers such as tires, tin cans, flower pots, roof gutters and children’s toys. The Asian tiger mosquito lays eggs in these places as well as in tree holes and other natural cavities. These types of mosquitoes are weak fliers and are generally found within 1/2 mile of where they hatch. The Asian tiger mosquito seldom ranges more than 200 yards from where it was hatched.

The best way to reduce your chances of contracting chikungunya is to reduce your chances of being bitten by the mosquitoes that carry it through integrated pest management. First, eliminate mosquito breeding sites by following the 5 Ts. Tip out any containers with standing water, Toss out grass clippings and leaf piles, Turn over anything that can hold water, tighten Tarps so they cannot hold water and Treat natural tree holes with larvacide or mosquito dunks. Remember that even a bottle cap full of water can provide an egg laying site for these nasty pests. Keeping gutters clean will also help as even small dams in gutters can provide breeding sites. Because these Aedes mosquitoes don’t travel far from breeding sites, working with your neighbors can greatly reduce the population.

There are other things you can do to prevent bites such as wearing long sleeves and pants, but more practical methods during a hot Texas summer include dressing in loose-fitting, light colored clothing. Mosquitoes are attracted to dark colors and body heat, and can easily bite through tight fitting clothing. Drinking beer will also make you more attractive to mosquitoes, so after mowing the lawn, down a sports drink instead. Avoid floral perfumes and lotions with the words “alpha hydroxy” in the ingredient list, and use repellents while enjoying outdoor activities. Finally, treat your yard to reduce the population around your home.

While chikungunya has been in the news lately, it is not new. It is just one of many mosquito-borne illnesses that humans have been dealing with for years. So relax, keep the tips above in mind, and enjoy your summer!